Variations on Earth's length of day (LOD) is most likely the reason for the different measurements of . You can read more about the variations of LOD from Phys.org article. Anyway, the variation is the magic word!
Let's picture our Earth as an electron... spinning and minding its own business and all the sudden its spinning frequency changes. What would happen in case of electron? Let's say that the spinning frequency increases a tiny fraction, say . We already know that due to electron's huge spinning frequency ( 1/s) and tiny size changes in the amount of circulating and bound FTEPs happen pretty quickly. In case of spinning frequency increase the amount of FTEPs bound to electron increases, hence electron mass would increase till there exists an equilibrium with the spinning frequency and the amount of bound FTEPs.
Earth's spinning frequency increase would increase also the amount of circulating and Earth bound FTEPs on top of the amount already bound to Earth mass. But due to Earth's size and slow spinning frequency those changes on the amount of FTEPs won't happen that quickly at all. What happens before the equilibrium between spinning frequency and the amount of additional bound FTEPs is achieved?
Increased spinning frequency would mean that outwards FTEP flow (in planet scale) would be greater than inwards FTEP flow. Inwards flow will eventually catch up. Based on Phys.org article that catching up might take as long as couple of months. During that time particles bound to Earth experience a situation where outwards flux consumes FTEPs around them and generate increased pressure on those particles' sides perpendicular to Earth's center of mass which is detected by sensitive measurements during those months. During those months inwards flux gets stronger and eventually the equilibrium is achieved and measurements converge towards its mean value.
In case of decreased Earth's spinning frequency things go reverse. There will be a temporary excess of FTEPs surrounding Earth's mass and also the pressure around the sides of particles perpendicular to Earth center of mass is decreased due to decreased Earth's spinning frequency. All this generates the illusion of the increased value for as described in previous blog post. Again, the equilibrium state between inwards and outwards fluxes will be achieved during the following months and settles down.
On top of measurements when Earth's spinning frequency increases or decreases I suggest that measurements should be done also when decrease happens a few months after the previous decrease (no increases in between).